Fast and Thermal Neutron Radiation Effects on GaN PIN Diodes

We studied how irradiation with fast (14 MeV) and thermal (<;0.4 eV) neutrons affected the properties of GaN PIN diodes, measuring their I-V characteristics before and after irradiation. Irradiation with fast neutrons caused the carrier removal effect when the reverse bias was low. Irradiation with thermal neutrons significantly increased the reverse-bias current, possibly because of damage to the passivation layer, defects induced in the GaN, and defects near the metal/GaN interface acting as tunneling sites. However, the forward current decreased both after fast neutron radiation and after thermal neutron radiation. Irradiation with thermal neutrons destroyed the SiO
₂
passivation layer. The crystal quality and optical properties of the GaN PIN diodes were characterized by examining changes in the photoluminescence (PL) and micro-Raman scattering spectra. As the fluence of neutrons increased, the yellow luminescence (YL) intensity increased because of the increase in V
_Ga
-related defects. Irradiation with fast and thermal neutrons destroyed the lattice integrity and changed the strain state of the devices, which was the main reason for the shift in the E
₂
^high
phonon mode.